1. Field of the Invention
The invent ion relates to an internal combustion engine having at least one bank of cylinders arranged in a row in at least one cylinder block, and having at least one fluid cooling system which is assigned to a respective cylinder bank and has at least one fluid channel which is formed in the cylinder block and which conducts fluid through the cylinder block as a water jacket adjacent to the cylinders in order to cool them. The fluid channel is delimited by a floor on the crankcase side in the cylinder block arranged between a cylinder head and a crankcase.
2. Discussion of the Prior Art
In order to cool cylinders of an internal combustion engine, it is customary to fashion a cooling water channel in the cylinder block in the form of a water box through which water flows as cooling medium and which surrounds the cylinders with a water jacket. The problem arises in this case, however, of turbulent flows which separate at the floor of the cooling water cavities, particularly in the case of a high rate of flow of the cooling water.
U.S. Pat. No. 4,455,972 describes a cylinder block with a water box, a wall which extends in the direction of flow dividing the water box into an upper section and a lower section. Seen in the direction of flow, in this case the dividing wall is fashioned obliquely in such a way that the upper section narrows, whereas the lower section widens. However, this arrangement is complicated and, owing to the additional wall, leads to turbulent flows which prevent thermal energy from being transported away by the cooling water.
European reference EP 0 671 552 B1 discloses a cooling system for a reciprocating internal combustion in which, an upper partial channel system assigned to the combustion chambers of the cylinders is open toward a cylinder head and forms a standard upper channel system together with cooling liquid chambers in the cylinder head. The cooling liquid chambers, located in the cylinder head, of the partial channel system in the cylinder block are supplied with cooling liquid by means of several passages distributed over a cylinder head base plate. However, in this case, too, substantial disadvantages are produced by additional instances of turbulence, in particular at the passages on the cylinder head base plate.
European reference EP 0 752 524 A1 discloses a cooling water jacket in a cylinder block for cylinders of an internal combustion engine in which, there is a stepwise narrowing of a flow width perpendicular to the direction of flow of the coolant in the direction of a crankcase sealing the cylinder block, that is to say a narrowing from top to bottom. However, these steps lead to undesired instances of turbulence in the water flow, and correspondingly hinder the cooling function of the flowing water.
European reference EP 0 196 635 A2 describes an internal combustion engine with at least two liquid-cooled cylinders situated one behind the other. A flow cross section of a cooling chamber between the cylinder block wall and cylinder wall is larger on one side of a respective cylinder than on a correspondingly opposite side. Wide and narrow sections alternate from cylinder to cylinder in the direction of flow. This has the disadvantage, however, that at corresponding transition sites between wide and narrow sections instances of turbulence arise in the cooling liquid flow which correspondingly restrict effective dissipation of thermal energy by the cooling water.
German reference DE 32 47 663 C1 discloses a cylinder block for an internal combustion engine in which, cooling water cavities in the cylinder block surround corresponding cylinders constructed in the cylinder block. A lower region of the cooling water cavities is partially filled up by an inserted, heat-resistant plastic material. Although the cylinder block can subsequently be appropriately adapted thereby to different requirements relating to the cooling conditions, this is complicated and cost-intensive. Furthermore, the filled-up cooling water cavity corresponds just to a cavity correspondingly finished to be smaller as early as during production of the cylinder block. No account is taken, in particular, of hydrodynamic conditions relating to turbulent flows which separate at the floor of the cooling water cavities, especially in the case of a high rate of flow of the cooling water.
German reference DE 24 17 925 C2 discloses a liquid-cooled multicylinder internal combustion engine, there being provided separately from a water jacket surrounding the cylinders an additional coolant chamber which narrows horizontally in the direction of flow and opens into the water jacket downstream. However, in this case different rates of flow and flow vectors of the merging flows give rise to a turbulent flow, especially in the region where opening occurs. These instances of turbulence prevent heat from being transported away by the cooling medium.
German reference DE-A 2 058 094 describes a liquid-cooled multicylinder internal combustion engine with a cooling water channel which is cast into a cooling water chamber of a crankcase and is open in the direction of a cylinder head, and whose cross section decreases continuously starting from a feed point for cooling water. This arrangement, too, does not take account of the fact that turbulent flows separate at the floor of the cooling water cavities, especially in the case of a high rate of flow of the cooling water.
German reference DE 41 40 772 A1 discloses a device for cooling lands between cylinders of a cylinder block of an internal combustion engine. These lands are arranged between cylinders cast together at least in the region of a cylinder block of an internal combustion engine, and have cooling channels. However, turbulent flow which impairs the cooling function of the coolant comes about precisely when the flow enters or exits the cooling channels of the lands.
It is therefore the object of the present invention to provide an internal combustion engine of the above-named type, the above-named disadvantages being, overcome, and optimized laminar flow of the cooling fluid over the entire length of a cooling channel in the cylinder block being achieved.
This object is achieved according to the invention by means of an internal combustion engine of the above-named type in which a cooling fluid system is assigned to a respective cylinder bank and has at least one fluid channel which is formed on the cylinder block so as to conduct fluid through the cylinder block as a fluid jacket adjacent to the cylinders in order to cool them. The fluid channel is delimited by a floor in the crankcase side in the cylinder block arranged between a cylinder head and the crank.
For this purpose, the invention provides that the floor of the fluid channel is fashioned in the form of a curved plane.
This has the advantage that this fashioning of the floor of the fluid channel makes available a higher laminar flow with optimum disposal of thermal energy without high power losses for a fluid pump through instances of turbulence in the fluid flow. This advantageously results in a fluid cooling system having a lower weight and a smaller required, fluid quantity.
The curved plane is expediently fashioned in such a way that several elevations which succeed one another in the direction of flow of the fluid in the fluid channel are formed with troughs situated correspondingly therebetween, the elevations and troughs preferably following one another cyclically.
Since the water box formed by the fluid channel is less extended in the region of the cylinders, it is possible to more effectively manage a cylinder pipe distortion during operation of the internal combustion engine.
A particularly good laminar flow over the entire length of the fluid channel in the cylinder block is achieved by virtue of the fact that the plane is a continuously differentiable curve in cross section.
Guidance of the fluid flow in the fluid channel that is particularly low in turbulence is achieved by virtue of the fact that the plane is a sinusoidal curve or cosinusoidal curve in cross section.
A homogeneous flow with far-reaching avoidance of instances of turbulence upon confluence of the fluid flows from fluid channels arranged on both sides of the cylinders is achieved by virtue of the fact that at an end of the fluid channel which is removed from the flow and at which the fluid channels on both sides are reunited, the floor has an elevation which extends in the direction of the cylinder head by a predetermined length and which deflects the respective fluid flows of the channels on both sides upwardly in the direction of a cylinder head before they flow together again.
In a preferred embodiment, the fluid channel is closed by a deck (closed deck) or open on the side of the cylinder head, the latter variant advantageously implementing a fluid-conducting connection to a fluid system in the cylinder head in the so-called open-deck design.
A particularly effective cooling and dissipation of thermal energy are achieved by virtue of the fact that the fluid is water.
Further features, advantages and advantageous refinements of the invention follow from the description of the invention given below with the aid of the attached drawing.